There are many causes of left pelvic pain, common or bone tumor, hip joint disease, femoral head necrosis, pelvic inflammatory disease, etc., as follows: a. Bone tumor: the presence of bone tumor on the patient’s pelvis, such as primary bone tumor or metastatic bone tumor, can lead to the existence of significant pain symptoms on the left pelvis, to make a clear diagnosis, you need to conduct local general X-ray, CT and MRI examination; Second, hip joint disease, femoral head necrosis: if the patient has left hip synovitis, hip osteoarthritis, hip dysplasia, and femoral head necrosis, it will also lead to significant pain symptoms in the left pelvis, and local MRI examination is needed to make a clear diagnosis; third, pelvic inflammatory disease: if the patient has pelvic inflammatory disease, stimulating the nerves on the pelvis, it will also cause obvious pain symptoms in the left pelvis.